Interlock and rebound control mechanism for sewing machines



April 2, 1940. M. MCCANN 2,195,890

mwmmocx AND nnsouun CONTROL MECHANISM FOP. SEWING MACHINES Filed Sept. 15, 1957 s Sheets-Sheet 1 994.4%? Michael Me C an/iv M. McCANN 2,195,890 INTERLOCK AND REBOUND CONTROL MECHANISM FOP. SEWING MACHINES April 2, 1940.-

3 Sheets-Sheet 2 Filed Sept. 15, 1957 Miekael Me Cwnn April2,1940., M. MOCANN 3 2,195,890

INTERLOCK AND REBOUND CONTROL MECHANISM FOR SEWING MACHINES Filed Sept. 15, 1937 3 Sheets-Sheet 5 [Michael 1% C am Patented Apr. 2, 1940 UNITED STATES INTERLOCK AND REBOUND CONTROL MECHANISM FOR SEWING MACHINES Michael McCann, Ozone Park, N. Y., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application September 15, 1937, Serial No. 163,927

8 Claims.

This invention relates to sewing machines and more particularly to that type of sewing machine designed to operate in a predetermined cycle and having a stop-motion device adapted to bring the machine to rest at the completion of said cycle, in a predetermined position, and also having a clamp mechanism adapted to hold the work in position to be operated upon by the stitch-forming mechanism.

One of the objects of the invention is to provide an improved interlock between the stopmotion device and the work-clamp lifting mechanism whereby lifting of the clamp is positively prevented until the machine has so nearly completed its cycle that lifting of the clamp will not cause damage to either the work or the machine needle.

Another object is to provide an interlock so constructed that it cannot interfere with the proper operation of the stop-motion device.

should the operator inadvertently attempt to raise the clamp prior to the tripping in of the stop-motion.

Another object is to provide an improved interlock between a stop-motion device and a clamplifting mechanism which will prevent starting of the machine whilethe clamp is in its raised position.

Still another object of the invention is to provide an improved rebound control means for preventing material reverse rotation or rebound of the main shaft of the machine when its forward rotation is suddenly arrested.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements or parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawings:

Fig. 1 is a side elevation of a button sewing machine embodying the present invention, the machine being shown in its position of rest.

Fig. 2 is a detail view, partly in section, of a portion of the machine illustrated in Fig 1, showing more particularly the interlock between the stop-motion and the clamp-lifting mechanism, the parts being shown in running position.

Fig. 3 is a sectional plan view of the parts shown in Fig. 2.

Fig. 4 is a sectional view taken substantially on the line 44 of Fig. 3 with the parts approaching their stop position and with the rebound control device shown in elevation. v

Fig. 5 is a view similar to Fig. 4 with the parts in stop position andwith the rebound control device shownin section.

Fig. 6 is a vertical sectional view taken substantially on the line 66 of Fig. 2.

-Fig. 7 is a view similar to Fig. 6, but showing the parts in a different position.

Fig. 8 is a rear end perspective view, partly in full lines and partly in dotted lines of the machineshown in Fig. 1, showing particularly the interlock between the clamp-lifting mechanism and the stop-motion mechanism; a portion of the figure being broken away to show the latch mechanism which is adapted to hold the stopmotion in machine driving position.

Referring more specifically to the drawings the invention is disclosed as embodied in a Singer Class 175 button sewing machine comprising a bed I, standard 2, bracket-arm 3 and a bracketarm head 4. Mounted in the head 4, for vertical reciprocation and lateral vibration, is a needlebar 5 carrying at its lower end, an eye-pointed needle 6. Cor erating with the needle in the formation of stitches is a looper 1, shown in dotted lines in Fig. l. Inasmuch as the means for actuating the needle and looper form no part of this invention, detailed illustration and description thereof is deemed unnecessary. Sufiice it, to say that they both are actuated by mechanism driven from a rotary shaft 8 journaled in the bed I. The shaft 8 has secured to it by a pin 9, the hub ID of a driving pulley ll adapted to be rotated by a belt 52. A loose pulley i3 is rotatably journaled on the, shaft 8 intermediate the pulley II and a hand-wheel I4 secured upon the end of the shaft. The belt I2 runs idly upon the loose pulley when the machine is at rest.

The machine is also provided with a buttonclamp, designated generally as C, and an underlying work-supporting plate l5, both of which are common to this type of button sewing machine. A pivot-pin i6 connects the clamp with conventional clamp actuating mechanism ll. The clamp is normally held depressed to its fullline position in Fig. 1 by a spring-pressed plunger ill but it may, at certain times, be lifted to its dotted line position to permit removal of the work. Journaled within, the arm 3 is a clamplifting rock-shaft is, having at its forward end an arm 20. connected by a chain 2! with the button-clamp C. Adjacent its rear end the shaft l9 has secured to it a second arm 22 engaged by the ofi-set end 23 of a vertical slide-rod 23 which is normally pressed upwardly by a coil spring 24 surrounding the rod 23 and interposed between a collar 25, secured to the rod by set screw 26, and a collar 2'! which loosely surrounds the rod 23 and which is held against downward movement by a fixed member 28, later to be ing it will be apparent that, unless otherwise prevented, downward movement of the chain 30, under the influence of a conventional treadle mechanism, will rock the shaft 3 and effect lifting of the button-clamp. Operation of the machine is controlled by a stop-motion mechanism which comprises a sliding frame 3| secured at one end by set screw 32 to a rod 33 slidingly mounted in fixed bearings 34 and 35 provided by the machine bed (see Fig. 3). Adjacent its other end the frame 3| is formed with an ear 36 having a bore 31 slidingly fitted upon a guidepin 38 threaded into the standard 2 as shown at 39 in Fig. 3. Adjacent the ear 36, the frame 3| carries a pin 40, to one end of which is secured a belt-shifting fork 4|. Secured to driving pulley II, as by nut 42, (see Fig. 2) is a stop-lug 43 adapted, at a certain time, to engage the projecting end of a buffer-spring 44 fitted within a socket 45 formed in the sliding frame 3| and held therein by the inner pointed ends of screws 46.

Means are provided for shifting the sliding frame 3| from the stop position shown in Fig. 1, in which the driving belt I2 is running idly on the loose pulley 3, to the position shown in Fig. 2 in which the driving belt is shown as engaging the tight pulley I I to drive the machine. This means comprises a conventional treadle (not shown) connected by a chain 41 with one arm 48 of a.- bell-crank lever 48. The lever 48 is fulcrumed upon a screw 49 carried by a machine-supporting base designated generally as B. The other arm 48*, of the lever 48, is adapted to engage a stud 50 carried by an extension 5| of a collar 5| secured upon the slide-rod 33. Thus it will be seen that downward movement of the chain 41, under the influence of the treadle, will cause the lever 48 to be rocked clockwise, as seen in Figs. 1 and 2, to shift the sliding stop-motion frame 3| and the parts carried thereby to the right. This movement is effected in opposition to the urge of a coil spring 52 surrounding the rod 33 and interposed between the fixed bearing 35 and a collar 53 secured to the rod. The rod 33 and the stopmotion frame 3| are adapted to be retained in the position shown in full lines in Fig. 3, with the spring 52 under tension, by a latch 54 pivotally mounted upon a stud screw 55 threaded into the machine bed. This latch is normally urged to turn counterclockwise, as seen in Fig. 3 by a coil spring 56, and is provided with a tooth 54- adapted to engage behind the collar 5|. The latch 54 is formed with an arm 54 which carries a finger 51 adapted, at a certain time during the operation of the machine, to be engaged by a campin 58 carried by a rotary element 59 of the machine which is driven by a worm 60 and wormwheel 6| from the main shaft 8. Engagement of the cam-pin 58 with the finger 5'! turns the latch clockwise, as seen in Fig. 3 and causes the tooth 54 to release the collar 5|. This permits the rod 33, and the frame 3| carried thereby, to be I shifted to the left under the influence of the spring 52 to shift the driving belt from the tight pulley to the loose pulley and to effect stopping of the machine as later will be described. Movement of the rod 33 to the left by the spring 52 is cushioned by a washer 62 surrounding the rod 33 adjacent the collar 53', the washer being adapted to engage a fixed wall 63 provided by the bed I It will be understood that when the parts are in the positions shown-in full lines in Fig. 3 the buffer-spring 44 is located at one side of the path of rotation of the stop-lug 43. However, when the latch 54 is tripped by the cam-pin 58 the rod 'the stop-motion is in running position.

33 and the parts carried thereby, including the frame 3| and the spring 44, are moved to the left and the spring is placed in the path of the stoplug. This tripping is effected at approximately the time the needle-bar starts downwardly to make the final stitch of a predetermined number of stitches. After this tripping the main shaft 8 makes approximately one complete rotation before the machine is finally brought to rest.

As shown most clearly in Figs. 4 and 5 the stop-motion frame also carries a rebound control device adapted to prevent material reverse rotation of the main shaft when the stop-lug 43 engages the buffer-spring at the completion of the cycle. This device preferably comprises a tubular member 64 pivotally mounted upon the pin 40, which also carries the belt shifter 4|. Within the member 64 is slidingly mounted a spring-pressed plunger 65 normally forced to the left by a coil spring 66. The tubular member 64 is normally maintained in the tilted position shown in Fig. 5 by the pressure of a coil spring 61 having one end fitted within a cavity in the frame 3| and the other end bearing upon the member 64. A stopscrew 68 limits the movement of the member 64 under the influence of the spring 61.

When the latch 54 is released and the stopmotion frame 3| is shifted outwardly by the spring 52, both the buffer-spring and the plunger 65 are placed within the path of rotation of the stop-lug 43. As the stop-lug approaches its final position in the last rotation of the main shaft it engages the underside of the plunger. 65 and tips the inner end of the plunger and its supporting member upwardly, as shown in Fig. 4, in opposition to the spring 61. As soon as the wall 43 of the lug 43 clears the end of the plunger 65 the spring 61 forces the member 64 and the plunger 65 downwardly to the position shown in Fig. 5. In this position the plunger 65 and the spring 66 act as a recoil device to prevent material reverse rotation of the main shaft and stop-lug under the influence of the buffer-spring 44.

Interlocks heretofore have been provided between clamp-llfting mechanism and stop-motion mechanism to prevent lifting of the clamp during running of the machine. Many of these interlocks have been controlled by the throwing in and throwing out of the stop-motion. In such devices lifting of the clamp is prevented while It is usual, however, for the stop-motion to be shifted to its stop position at the beginning of the flnal stitch of a cycle. Therefore in most of the interlocks heretofore provided the interlock was not effective at the most critical time, that is, during the making of the last stitch. It has been found that, in endeavoring to obtain maximum production, operators will anticipate the stopping of the machine and sometimes will actuate the clamp-lifting treadle and attempt to remove the work immediately the stop-motion has been tripped to stop the machine and during the formation of the last stitch. This effects relative'lateral movement between the work and the needle and results in damage to one or the other.

As hereinbefore stated, this invention provides an improved interlock between the clamp-lifting mechanism and the stop-motion mechanism whereby lifting of the clamp is positively precluded until the machine has so nearly reached its stop position that the needle is well above the work in its final up stroke. When the parts have reached that position raising of the clamp will not damage either the work or the needle.

This interlock comprises a locking-bar 68 slidingly mounted in a fixed casing 28 secured to the machine standard by screws 65. As shown most clearly in Figs. 3 and 6 the clamp-lifting sliderod 23 is formed with a. notch 23 adapted to receive the locking-bar 68. Likewise the lockingbar is formed with an aperture 68 adapted, in one ofthe positions thereof, to permit passage of the rod 23. It will readily be perceived that when the parts are in the position shown in Figs. 3 and 6, with the bar 68 located between the upper and lower walls of the notch 23*, the rod 23 may not be depressed any substantial amount and therefore the button-clamp C may not be lifted. However, when the locking-bar 68 has been moved to the left from the position shown in Fig. 3, to align the aperture 68 with the rod 23, the rod 23 may be depressed and therefore the clamp may be lifted. When the rod 23 has been depressed as shown in Fig. 7 during the lifting of the clamp, the aperture 68 in the bar 68 partially embraces the cylindrical portion of the rod 23 and therefore prevents endwise movement of the bar 68. This prevents the stopmotion from being shifted into running position as later will be described. The bar 68 is normally urged to the left, as seen in Figs. 2 and 3, by a coil spring l0, seated within a bore formed in the inner end of the bar 68, and having its projecting end bearing against a block ll secured in the casing 28. The outer end of the bar 68 normally bears against a plate 12 adjustably secured to the sliding stop-motion frame 3|.

From the foregoing it will be understood that when the stop-motion is shifted to running position the locking bar is shifted inwardly to the position shown in Fig. 3 and thereby locks the rod 23 against endwise movement.

When the stop-motion is shifted to stop position'and the bar 68 is moved outwardly by the spring 10 the rod 23 is released and may be depressed and the button-clamp may be raised. Likewise while the rod 23 is depressed to lift the clamp it looks the bar 68 against inward movement and therefore the stop-motion cannot be shifted to start the machine while the clamp is in raised position.

To the end that the bar'68 may not be shifted outwardly and thereby release the rod 23 irnmediately the stop motion has been shifted to stop position, there is provided a latch mechanism controlled by a delayed-action trip device, which maintains the bar in its retracted position, in which it holds the rod 23 against downward movement, until the machine has nearly reached its final position of rest, or, to be more specific, until the main shaft and the stop-lug 43 have approached within approximately twenty degrees of their stop position and the needle has been lifted well above the work. This latch mechanism comprises a latch-lever 13 located mainly within an aperture in the casing 28 and pivotally and slidingly mounted on a pivot pin 1'4 in said casing. Intermediate its ends the latch-lever I3 is'formed with a tooth 15 adapted to engage the wall 16 of a notch I6 formed in the underside of the bar 18. As shown most clearly in Fig. 2, the latch-lever is normally urged to the right by a coil spring 18 interposed between a wall of the casing 28 and a head l3 on the latch-lever. The pivot-pin 14 passes through an elongated aperture in the latch-lever and therefore the latch is permitted to have a limited amount of endwise movement. The latch-lever is normally pressed upwardly, to place the tooth 15 in the path of the wall 16, by a leaf-spring 8| secured to the underside of the casing 28 and bearing upwardly on the latch-lever. The latch-lever is formed with a free end l3 which underlies the outer end of the member 64 of the rebound controller.

It will be understood that when the stopbar 68 which thereupon moves outwardly under the influence of the spring "and places the aperture 68* in position so that the rod 23 may be depressed and the button-clamp raised.

Inasmuch as the only connection between the slide-bar 68 and the stop-motion frame 3| is the abutment of the end of the bar against the plate 12 carried by the stop-motion frame, should the operator attempt to depress the clamp-lifting treadle before the stop-motion frame has been shifted into its stop position, binding of the rod 23 on the locking-bar 68 cannot prevent the stop-motion from performing its intended function, as the frame is free to move away from the end of the bar.

To the end that the device will not be rendered inoperative should the operator permaturely actuate the clamp-lifting treadle, the spring 19 serves to shift the latch-lever l3 endwise to the right as shown in dotted lines in Fig. 2, immediately the lever is rocked to disconnect its tooth 15 from the wall of the notch 16 in the lockingbar 68. Thus should the operator prematurely actuate the clamp-lifting treadle and thereby cause the upper wall of the notch 23 of the rod 23 to bear upon the bar 68 and prevent it from moving outwardly, when the latch I3 is depressed by the element 64 the tooth 15 will be moved laterally out of alignment with the notch 16 and therefore as soon as the operator releases the pressure on the clamp-lifting treadle the bar 68 will be moved outwardly and will align the aperture (i8 therein with the rod 23, whereupon the rod may be depressed and the clamp lifted.

Obviously when the rod 23 is depressed and the cylindrical portion thereof is located within the aperture 68 the bar 68 cannot be moved in- I wardly and therefore the stop-motion cannot be actuated to start the machine while the clamp is in raised position.

When the stop-motion frame is shifted inwardly to start the machine, the bar 68 also is moved inwardly in opposition to the spring I0 and, as soon as'the notch 16 in the bar 68 passesmotion mechanism controlling the rotation of said shaft; an interlock between said clamplifting mechanism and said stop-motion mechanism, comprising a slide-bar adapted to be shifted in one direction and placed under spring pressure by said stop-motion when the latter is actuated to initiate rotation of said shaft, said slide-bar in one position, serving to prevent actuation of said clamp-lifting mechanism and in another position to permit actuation thereof, and means to prevent said slide-bar from moving-in the opposite direction under the influence of said spring pressure to release said clamp-lifting mechanism until said stop-motion has been actuated to effect stopping of the shaft and said shaft has thereafter made at least one-half rotation.

2. In a sewing machine having a clamp, means to lift said clamp, a rotary shaft, stitch-forming mechanism actuated from said shaft, and a stopmotion mechanism controlling the rotation of said shaft, an interlock between said clamplifting mechanism and said stop-motion mechanism comprising a slide-bar adapted in one position to lock said clamp-lifting mechanism against actuation, means actuated by said stop-motion to shift said slide-bar to its locking position when said stop-motion is actuated to initiate rotation of said shaft, means tending to shift said bar out of its locking position when said stop-motion is actuated to effect stopping of said shaft, a latch temporarily holding said bar in its locking position, and means actuated by said shaftin the final portion of its last rotation to render said latch ineffective.

3. In a sewing machine having a clamp, means to lift said clamp, a rotary shaft, a stop-motion controlling the rotation of said shaft, said stop motion including a shiftable frame adapted in one position to effect rotation of said shaft and in another position to stop rotation thereof, a lug rotatable with said shaft, and a cooperating buffer element carried by said frame; an interlock between said clamp-lifting mechanism and said stop-motion comprising a slide-bar adapted in one position to lock said clamp-lifting mechanism against actuation, means actuated by said sliding frame when shifted to its running-position to move said slide-bar to its locking position, means tending to shift said slide-bar out of its locking position, a latch device holding said bar in its locking position when said frame is moved to stop position, and a trip device carried by said shiftable frame and actuated by said rotatable lug to release said latch mechanism as said shaft approaches its stop position.

4. In a sewing machine having a clamp, means to lift said clamp, a rotary shaft, and a stopmotion controlling the rotation of said shaft; an interlock between said clamp-lifting mechanism and said stop-motion mechanism comprising a slide-bar adapted in one position to lock said clamp-lifting mechanism against actuation, means actuated by said stop-motion when operated to effect rotation of said shaft to move said slide-bar to its locking position, means tending to shift said slide-bar out of its locking position, a latch device holding said slide-bar in its locking position when said stop-motion is operated to stop rotation of said shaft, a member pivotally mounted on said stop-motion and adapted, when actuated, to trip said latch device, and means rotatable with said shaft to rock said member and thereby release said latch just prior to the stopping of said shaft.

5. In a sewing machine having a clamp, means to lift said clamp, a rotary shaft, and a stopmotion controlling the rotation of said shaft; an interlock between said clamp-lifting mechanism and said stop-motion, said interlock comprising a rod movable axially by said clamp-lifting means, a slide-bar mounted transversely of said rod and arranged partially in the plane thereof,

said slide-bar being provided with an aperture adapted in one position of the slide-bar to permit passage of said rod and a portion adapted in another position of said slide-bar to lock said rod against movement, means rendered effective by said stop-motion when it is actuated to effect rotation of said shaft to shift said slide-bar to its rod-locking position, means tending to shift said bar to a rod-unlocking position, a latch adapted to engage said slide-bar to maintain it in its locking position after said stop-motion has been actuated to effect stopping of said shaft, and means actuated by said shaft as it approaches its stop position to release said latch thereby to permit said slide-bar to return to its rod-unlocking position.

6. An interlock between a clamp-lifting mechanism and a stop-motion mechanism as set forth in the preceding claim in which the slidebar is provided with a notch adapted to receive a tooth on the latch and in which the latch is arranged parallel to the slide-bar and is mounted to have both sliding and pivotal movements, means actuated by the shaft as it approaches its stop position to move said latch about its pivot to cause the tooth thereof to be disengaged from the notch in said slide-bar and spring means thereafter acting to shift said latch endwise to place said tooth out of register with said notch.

'7. In a sewing machine having a frame, a clamp, means to lift said clamp, a rotary shaft, and a stop-motion controlling the rotation of said shaft; an interlock between said clamplifting means and said stop-motion, said interlock comprising a casing secured to said frame, a rod connected with said clamp-lifting means and movable vertically through an aperture in said casing, a locking-bar slidingly mounted in said casing transversely of said rod and provided with an aperture adapted in one position of the bar, to permit passage of said rod and a portion adapted in another position of said bar to lock said rod against movement, a latch member pivotally mounted in said casing and having a portion adapted to engage said locking-bar to maintain it in its rod-locking position, and means actuated by said shaft to cause said latch to release said locking-bar.

8. A sewing machine combining a rotary shaft, a clamp, clamp-lifting mechanism, a stop-motion controlling the rotation of said shaft, an interlock between said clamp-lifting mechanism and said stop-motion including an endwise movable spring-pressed locking-bar adapted to prevent lifting of said clamp while said stop-motion is in shaft-driving position, a latch-lever arranged lengthwise of said locking-bar and having a tooth engaging the latter for maintaining said interlock eflective when said stop-motion is moved to a shaft-stopping position, and a delayed-action means operated by the rotation of said shaft for tripping said latch-lever when said shaft approaches its stop position.

MICHAEL McCANN. 

